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Message-ID: <20140115042457.GI1992@bbox>
Date: Wed, 15 Jan 2014 13:24:57 +0900
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: Jerome Marchand <jmarchan@...hat.com>,
Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] zram: rework reported to end-user zram statistics
Hello Sergey,
On Tue, Jan 14, 2014 at 12:37:40PM +0300, Sergey Senozhatsky wrote:
> 1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats
> `show' functions and reduce code duplication.
>
> 2) Account and report back to user numbers of failed READ and WRITE
> operations.
>
> 3) Remove `good' and `bad' compressed sub-requests stats. RW request may
> cause a number of RW sub-requests. zram used to account `good' compressed
> sub-queries (with compressed size less than 50% of original size), `bad'
> compressed sub-queries (with compressed size greater that 75% of original
> size), leaving sub-requests with compression size between 50% and 75% of
> original size not accounted and not reported. Account each sub-request
> compression size so we can calculate real device compression ratio.
>
> 4) reported zram stats:
> - num_writes -- number of writes
> - num_reads -- number of reads
> - pages_stored -- number of pages currently stored
> - compressed_size -- compressed size of pages stored
> - pages_zero -- number of zero filled pages
> - failed_read -- number of failed reads
> - failed_writes -- can happen when memory is too low
> - invalid_io -- non-page-aligned I/O requests
> - notify_free -- number of swap slot free notifications
> - memory_used -- zs pool zs_get_total_size_bytes()
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
So this patch includes some clean up and behavior changes?
Please seaprate them and each patch in behavior change includes
why it's bad or good(ie, motivation).
It could make reviewer/maintainer happy, even you because
some of them could be picked up and other things could be dropped.
Sorry for the bothering you.
Thanks.
> ---
> drivers/block/zram/zram_drv.c | 167 ++++++++++++------------------------------
> drivers/block/zram/zram_drv.h | 17 ++---
> 2 files changed, 54 insertions(+), 130 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 2a7682c..8bddaff 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -42,6 +42,17 @@ static struct zram *zram_devices;
> /* Module params (documentation at end) */
> static unsigned int num_devices = 1;
>
> +#define ZRAM_ATTR_RO(name) \
> +static ssize_t zram_attr_##name##_show(struct device *d, \
> + struct device_attribute *attr, char *b) \
> +{ \
> + struct zram *zram = dev_to_zram(d); \
> + return sprintf(b, "%llu\n", \
> + (u64)atomic64_read(&zram->stats.name)); \
> +} \
> +static struct device_attribute dev_attr_##name = \
> + __ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
> +
> static inline int init_done(struct zram *zram)
> {
> return zram->meta != NULL;
> @@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev)
> return (struct zram *)dev_to_disk(dev)->private_data;
> }
>
> -static ssize_t disksize_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n", zram->disksize);
> -}
> -
> -static ssize_t initstate_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%u\n", init_done(zram));
> -}
> -
> -static ssize_t num_reads_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n",
> - (u64)atomic64_read(&zram->stats.num_reads));
> -}
> -
> -static ssize_t num_writes_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n",
> - (u64)atomic64_read(&zram->stats.num_writes));
> -}
> -
> -static ssize_t invalid_io_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n",
> - (u64)atomic64_read(&zram->stats.invalid_io));
> -}
> -
> -static ssize_t notify_free_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n",
> - (u64)atomic64_read(&zram->stats.notify_free));
> -}
> -
> -static ssize_t zero_pages_show(struct device *dev,
> - struct device_attribute *attr, char *buf)
> -{
> - struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
> -}
> -
> -static ssize_t orig_data_size_show(struct device *dev,
> +static ssize_t memory_used_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> + u64 val = 0;
> struct zram *zram = dev_to_zram(dev);
> + struct zram_meta *meta = zram->meta;
>
> - return sprintf(buf, "%llu\n",
> - (u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
> + down_read(&zram->init_lock);
> + if (init_done(zram))
> + val = zs_get_total_size_bytes(meta->mem_pool);
> + up_read(&zram->init_lock);
> + return sprintf(buf, "%llu\n", val);
> }
>
> -static ssize_t compr_data_size_show(struct device *dev,
> +static ssize_t disksize_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct zram *zram = dev_to_zram(dev);
> -
> - return sprintf(buf, "%llu\n",
> - (u64)atomic64_read(&zram->stats.compr_size));
> + return sprintf(buf, "%llu\n", zram->disksize);
> }
>
> -static ssize_t mem_used_total_show(struct device *dev,
> +static ssize_t initstate_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - u64 val = 0;
> + u32 val = 0;
> struct zram *zram = dev_to_zram(dev);
> - struct zram_meta *meta = zram->meta;
> -
> down_read(&zram->init_lock);
> - if (init_done(zram))
> - val = zs_get_total_size_bytes(meta->mem_pool);
> + val = init_done(zram);
> up_read(&zram->init_lock);
> -
> - return sprintf(buf, "%llu\n", val);
> + return sprintf(buf, "%u\n", val);
> }
>
> /* flag operations needs meta->tb_lock */
> @@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index)
> {
> struct zram_meta *meta = zram->meta;
> unsigned long handle = meta->table[index].handle;
> - u16 size = meta->table[index].size;
>
> if (unlikely(!handle)) {
> /*
> @@ -302,21 +251,15 @@ static void zram_free_page(struct zram *zram, size_t index)
> */
> if (zram_test_flag(meta, index, ZRAM_ZERO)) {
> zram_clear_flag(meta, index, ZRAM_ZERO);
> - atomic_dec(&zram->stats.pages_zero);
> + atomic64_dec(&zram->stats.pages_zero);
> }
> return;
> }
>
> - if (unlikely(size > max_zpage_size))
> - atomic_dec(&zram->stats.bad_compress);
> -
> zs_free(meta->mem_pool, handle);
>
> - if (size <= PAGE_SIZE / 2)
> - atomic_dec(&zram->stats.good_compress);
> -
> - atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
> - atomic_dec(&zram->stats.pages_stored);
> + atomic64_sub(meta->table[index].size, &zram->stats.compressed_size);
> + atomic64_dec(&zram->stats.pages_stored);
>
> meta->table[index].handle = 0;
> meta->table[index].size = 0;
> @@ -362,7 +305,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
> static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
> u32 index, int offset, struct bio *bio)
> {
> - int ret;
> + int ret = -EINVAL;
> struct page *page;
> unsigned char *user_mem, *uncmem = NULL;
> struct zram_meta *meta = zram->meta;
> @@ -406,6 +349,8 @@ out_cleanup:
> kunmap_atomic(user_mem);
> if (is_partial_io(bvec))
> kfree(uncmem);
> + if (ret)
> + atomic64_inc(&zram->stats.failed_reads);
> return ret;
> }
>
> @@ -459,7 +404,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> zram_set_flag(meta, index, ZRAM_ZERO);
> write_unlock(&zram->meta->tb_lock);
>
> - atomic_inc(&zram->stats.pages_zero);
> + atomic64_inc(&zram->stats.pages_zero);
> ret = 0;
> goto out;
> }
> @@ -478,7 +423,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> }
>
> if (unlikely(clen > max_zpage_size)) {
> - atomic_inc(&zram->stats.bad_compress);
> clen = PAGE_SIZE;
> src = NULL;
> if (is_partial_io(bvec))
> @@ -516,11 +460,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> write_unlock(&zram->meta->tb_lock);
>
> /* Update stats */
> - atomic64_add(clen, &zram->stats.compr_size);
> - atomic_inc(&zram->stats.pages_stored);
> - if (clen <= PAGE_SIZE / 2)
> - atomic_inc(&zram->stats.good_compress);
> -
> + atomic64_add(clen, &zram->stats.compressed_size);
> + atomic64_inc(&zram->stats.pages_stored);
> out:
> if (locked)
> mutex_unlock(&meta->buffer_lock);
> @@ -586,23 +527,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
>
> static void zram_init_device(struct zram *zram, struct zram_meta *meta)
> {
> - if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
> - pr_info(
> - "There is little point creating a zram of greater than "
> - "twice the size of memory since we expect a 2:1 compression "
> - "ratio. Note that zram uses about 0.1%% of the size of "
> - "the disk when not in use so a huge zram is "
> - "wasteful.\n"
> - "\tMemory Size: %lu kB\n"
> - "\tSize you selected: %llu kB\n"
> - "Continuing anyway ...\n",
> - (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
> - );
> - }
> -
> /* zram devices sort of resembles non-rotational disks */
> queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
> -
> zram->meta = meta;
> pr_debug("Initialization done!\n");
> }
> @@ -774,14 +700,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
> disksize_show, disksize_store);
> static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
> static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
> -static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
> -static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
> -static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
> -static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
> -static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
> -static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
> -static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
> -static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
> +static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL);
> +
> +ZRAM_ATTR_RO(num_reads);
> +ZRAM_ATTR_RO(num_writes);
> +ZRAM_ATTR_RO(pages_stored);
> +ZRAM_ATTR_RO(invalid_io);
> +ZRAM_ATTR_RO(notify_free);
> +ZRAM_ATTR_RO(pages_zero);
> +ZRAM_ATTR_RO(compressed_size);
>
> static struct attribute *zram_disk_attrs[] = {
> &dev_attr_disksize.attr,
> @@ -789,12 +716,12 @@ static struct attribute *zram_disk_attrs[] = {
> &dev_attr_reset.attr,
> &dev_attr_num_reads.attr,
> &dev_attr_num_writes.attr,
> + &dev_attr_pages_stored.attr,
> &dev_attr_invalid_io.attr,
> &dev_attr_notify_free.attr,
> - &dev_attr_zero_pages.attr,
> - &dev_attr_orig_data_size.attr,
> - &dev_attr_compr_data_size.attr,
> - &dev_attr_mem_used_total.attr,
> + &dev_attr_pages_zero.attr,
> + &dev_attr_compressed_size.attr,
> + &dev_attr_memory_used.attr,
> NULL,
> };
>
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index e81e9cd..277023d 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -64,22 +64,19 @@ enum zram_pageflags {
> struct table {
> unsigned long handle;
> u16 size; /* object size (excluding header) */
> - u8 count; /* object ref count (not yet used) */
> - u8 flags;
> + u16 flags;
> } __aligned(4);
>
> struct zram_stats {
> - atomic64_t compr_size; /* compressed size of pages stored */
> - atomic64_t num_reads; /* failed + successful */
> - atomic64_t num_writes; /* --do-- */
> - atomic64_t failed_reads; /* should NEVER! happen */
> + atomic64_t num_writes; /* number of writes */
> + atomic64_t num_reads; /* number of reads */
> + atomic64_t pages_stored; /* no. of pages currently stored */
> + atomic64_t compressed_size; /* compressed size of pages stored */
> + atomic64_t pages_zero; /* no. of zero filled pages */
> + atomic64_t failed_reads; /* no. of failed reads */
> atomic64_t failed_writes; /* can happen when memory is too low */
> atomic64_t invalid_io; /* non-page-aligned I/O requests */
> atomic64_t notify_free; /* no. of swap slot free notifications */
> - atomic_t pages_zero; /* no. of zero filled pages */
> - atomic_t pages_stored; /* no. of pages currently stored */
> - atomic_t good_compress; /* % of pages with compression ratio<=50% */
> - atomic_t bad_compress; /* % of pages with compression ratio>=75% */
> };
>
> struct zram_meta {
> --
> 1.8.5.2.487.g7559984
>
> --
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--
Kind regards,
Minchan Kim
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